Polymers containing dibenzocycloheptane structural units

ABSTRACT

The invention relates to polymers containing dibenzocycloheptene structural units, to a method for the production thereof, and to blends and formulations containing said polymers. The invention further relates to the use of the polymers or blends according to the invention in electronic devices and to electronic devices, in particular OLEDs, containing the polymers or blends according to the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application (under 35 U.S.C. §371)of PCT/EP2013/000232, filed Jan. 26, 2013, which claims benefit ofEuropean Application No. 12001158.0, filed Feb. 22, 2012, both of whichare incorporated herein by reference in their entirety.

The present application relates to polymers containingdibenzocycloheptane structural units, to process for the preparationthereof and to blends and formulations comprising these polymers. Thepresent application furthermore relates to the use of the polymers orblends according to the invention in electronic devices and toelectronic devices, in particular OLEDs, comprising the polymers orblends according to the invention.

Compounds such as the polymers according to the invention are beingdeveloped for a number of different applications which can be ascribedin the broadest sense to the electronics industry. The structure oforganic electroluminescent devices (OLEDs) in which these organicsemiconductors are preferably employed, inter alia, as functionalmaterials is described, for example, in U.S. Pat. Nos. 4,539,507,5,151,629, EP 0676461 and WO 98/27136.

The prior art discloses various polymeric materials which are suitablefor use in organic electroluminescent devices. Thus, for example,compounds based on monomer units such as spirobifluorene, fluorene,indenofluorene, phenanthrene or dihydrophenanthrene are disclosed in WO04/041901, WO 04/113412 and WO 05/014689.

However, there continues to be a demand for novel materials for use inorganic electronic devices, in particular with regard to an improvementof the devices in the following respects:

-   -   1. Materials having a larger band gap are required, so that        deeper-blue singlet emission can be achieved for display        applications having a large colour space. Larger band gaps in        polymers would additionally enable these to be used as host        materials not only for red, but also for green triplet emission.    -   2. The lifetime and efficiency of organic electroluminescent        devices should be increased further, in particular in the case        of blue-emitting systems and with respect to high-value        applications.

The present invention is thus based on the object of providing novelmaterials for electronic devices which have a larger band gap andimprove the lifetime and efficiency of organic electroluminescentdevices.

Surprisingly, it has been found that polymers containingdibenzocycloheptane units can successfully be employed as materials inelectronic devices, preferably organic electroluminescent devices.

The present application thus relates to a polymer containing one or morestructural units of the following formula (I),

where

-   R¹, R² can be on each occurrence, identically or differently, H, D,    F, OH, N(R³)₂, a straight-chain, branched or cyclic alkyl, alkoxy or    thioalkoxy group having 1 to 40 C atoms, in which, in addition, one    or more H atoms may be replaced by F and in which, in addition, one    or more non-adjacent CH₂ groups may be replaced by O, S, Si(R³)₂,    Ge(R³)₂, BR³, NR³, PR³, CO, C═S, C═Se, C═NR³, PO(R³), PS(R³),    R³C═CR³, C≡C, SO, SO₂, COO, O(CO)O or CONR³, or a mono- or    polycyclic, aromatic or heteroaromatic ring system;-   R³ can be on each occurrence, identically or differently, H, F, a    straight-chain, branched or cyclic alkyl, alkoxy or thioalkoxy group    having 1 to 40 C atoms, in which, in addition, one or more H atoms    may be replaced by F and in which, in addition, one or more    non-adjacent CH₂ groups may be replaced by O, CO, COO or O(CO)O, or    a mono- or polycyclic, aromatic or heteroaromatic ring system;-   m, n can be, independently of one another, identically or    differently, 0, 1, 2 or 3, preferably 0 or 1 and particularly    preferably 0;    -   and the dashed lines represent the bonds to the adjacent        structural units in the polymer.

The polymers according to the invention preferably contain 2 to 10,000recurring units, where the term “polymer” in the present application isintended to encompass both polymers and also dendrimers and oligomers.The oligomeric compounds according to the invention have 2 to 9recurring units. Preferred polymers and dendrimers according to theinvention contain in total 10 to 10,000 recurring units. The degree ofbranching DB of the polymers and dendrimers here can be between 0(linear polymer without branching points) and 1 (fully brancheddendrimer).

The polymers according to the invention preferably have a molecularweight M_(w) in the range from 1,000 to 2,000,000 g/mol, particularlypreferably a molecular weight M_(w) in the range from 100,000 to1,500,000 g/mol and very particularly preferably a molecular weightM_(w) in the range from 150,000 to 1,000,000 g/mol. The molecular weightM_(w) is determined by means of GPC(=gel permeation chromatography)against an internal polystyrene standard.

In the embodiment according to the invention, the proportion of thestructural units of the formula (I) in the polymer is 0.01 to 100 mol %,preferably 1 to 95 mol %, particularly preferably 10 to 80 mol % andvery particularly preferably 30 to 60 mol %.

The term “mono- or polycyclic, aromatic ring system” in the presentapplication is taken to mean an aromatic ring system having 6 to 60,preferably 6 to 30, particularly preferably 6 to 14 and veryparticularly preferably 6 to 10 aromatic ring atoms, which does notnecessarily contain only aromatic groups, but instead in which aplurality of aromatic units may also be interrupted by a shortnon-aromatic unit (<10% of the atoms other than H, preferably <5% of theatoms other than H), such as, for example, sp³-hybridised C atom or O orN atom, CO group, etc. Thus, for example, systems such as9,9′-spirobifluorene, 9,9′-diarylfluorene, etc., are also intended to betaken to be aromatic ring systems.

The aromatic ring systems may be mono- or polycyclic, i.e. they may haveone ring (for example phenyl) or a plurality of rings, which may also becondensed (for example naphthyl) or covalently linked (for examplebiphenyl), or contain a combination of condensed and linked rings.

Preferred aromatic ring systems are, for example, phenyl, biphenyl,terphenyl, naphthyl, binaphthyl, phenanthrene, dihydrophenanthrene,pyrene, dihydropyrene, chrysene, fluorene, indene, indenofluorene andspirobifluorene.

The term “mono- or polycyclic, heteroaromatic ring system” in thepresent application is taken to mean an aromatic ring system having 5 to60, preferably 5 to 30, particularly preferably 5 to 20 and veryparticularly preferably 5 to 9 aromatic ring atoms, where one or more ofthese atoms is (are) a heteroatom.

The “mono- or polycyclic, heteroaromatic ring system” does notnecessarily contain only aromatic groups, but instead may also beinterrupted by a short non-aromatic unit (<10% of the atoms other thanH, preferably <5% of the atoms other than H), such as, for example,sp³-hybridised C atom or O or N atom, CO group, etc.

The heteroaromatic ring systems may be mono- or polycyclic, i.e. theymay have one ring or a plurality of rings, which may also be condensedor covalently linked (for example pyridylphenyl), or contain acombination of condensed and linked rings. Preference is given to fullyconjugated heteroaryl groups.

Preferred heteroaromatic ring systems are, for example, 5-memberedrings, such as pyrrole, pyrazole, imidazole, 1,2,3-triazole,1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole,isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole,1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole,1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-memberedrings, such as pyridine, pyridazine, pyrimidine, pyrazine,1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine,1,2,3,4-tetrazine, 1,2,3,5-tetrazine, or condensed groups, such asindole, isoindole, indolizine, indazole, benzimidazole, benzotriazole,purine, naphthimidazole, phenanthrimidazole, pyridimidazole,pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole,anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran,isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine,benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline,benzoisoquinoline, acridine, phenothiazine, phenoxazine,benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine,azacarbazole, benzocarboline, phenanthridine, phenanthroline,thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene,isobenzothiophene, dibenzothiophene, benzothiadiazothiophene orcombinations of these groups.

The mono- or polycyclic, aromatic or heteroaromatic ring system may beunsubstituted or substituted. Substituted in the present applicationmeans that the mono- or polycyclic, aromatic or heteroaromatic ringsystem have one or more substituents R¹.

Preferred structural units of the formula (I) are represented by theformulae (Ia) to (Ic) shown below, where the formula (Ia) isparticularly preferred.

The dashed lines in the formulae (Ia), (Ib) and (Ic) here represent thebonds to the adjacent structural units in the polymer. R¹, R², m and nin the formulae (Ia) to (Ic) here can adopt the meanings indicated forR¹, R², m and n in relation to formula (I).

A preferred structural unit of the formula (Ia) is represented by theformula (Ia1) shown below.

A particularly preferred structural unit of the formula (Ia) isrepresented by the formula (Ia2) shown below.

The dashed lines in the formulae (Ia1) and (Ia2) here represent thebonds to the adjacent structural units in the polymer. The radicals R¹in the formulae (Ia1) and (Ia2) here can adopt the meanings indicatedfor R¹ in relation to formula (I).

R¹ and R² in the formulae (I), (Ia) to (Ic) and (Ia1) and (Ia2) ispreferably on each occurrence, identically or differently, astraight-chain or branched alkyl or alkoxy group having 1 to 10 C atoms,particularly preferably having 1 to 6 C atoms.

In a preferred embodiment of the present invention, the polymeraccording to the invention, besides one or more structural units of theformula (I), also contains at least one further structural unit which isdifferent from the structural unit of the formula (I). These are, interalia, those as disclosed and extensively listed in WO 02/077060 A1 andin WO 2005/014689 A2. These are regarded as part of the presentapplication by way of reference. The further structural units canoriginate, for example, from the following classes:

-   group 1: units which influence the hole-injection and/or    hole-transport properties of the polymers;-   group 2: units which influence the electron-injection and/or    electron-transport properties of the polymers;-   group 3: units which have combinations of individual units from    group 1 and group 2;-   group 4: units which modify the emission characteristics to such an    extent that electrophosphorescence can be obtained instead of    electrofluorescence;-   group 5: units which improve transfer from the singlet state to the    triplet state;-   group 6: units which influence the emission colour of the resultant    polymers;-   group 7: units which are typically used as polymer backbone;-   group 8: units which influence the film morphology and/or the    rheology of the resultant polymers.

Structural units from group 1 which have hole-injection and/orhole-transport properties are, for example, triarylamine, benzidine,tetraaryl-para-phenylenediamine, triarylphosphine, phenothiazine,phenoxazine, dihydrophenazine, thianthrene, dibenzo-para-dioxin,phenoxathiyne, carbazole, azulene, thiophene, pyrrole and furanderivatives and further O-, S- or N-containing heterocycles having ahigh HOMO (HOMO=highest occupied molecular orbital). These arylaminesand heterocycles preferably result in an HOMO in the polymer of greaterthan −5.8 eV (against vacuum level), particularly preferably greaterthan −5.5 eV.

Structural units from group 2 which have electron-injection and/orelectron-transport properties are, for example, pyridine, pyrimidine,pyridazine, pyrazine, oxadiazole, quinoline, quinoxaline, anthracene,benzanthracene, pyrene, benzimidazole, triazine, ketone, phosphine oxideand phenazine derivatives, but also triarylboranes and further O-, S- orN-containing heterocycles having a low LUMO (LUMO=lowest unoccupiedmolecular orbital). These units in the polymer preferably result in anLUMO of less than −1.5 eV (against vacuum level), particularlypreferably less than −2.0 eV.

It may be preferred for the polymers according to the invention tocontain units from group 3 in which structures which influence the holemobility and structures which influence the electron mobility (i.e.units from group 1 and 2) are bonded directly to one another or tocontain structures which influence both the hole mobility and theelectron mobility. Some of these units can serve as emitters and shiftthe emission colour into the green, yellow or red. Their use is thussuitable, for example, for the generation of other emission colours fromoriginally blue-emitting polymers.

Structural units from group 4, so-called triplet emitter units, arethose which are able to emit light from the triplet state with highefficiency, even at room temperature, i.e. exhibitelectrophosphorescence instead of electrofluorescence, which frequentlycauses an increase in the energy efficiency. A triplet emitter unit inthe present application is taken to mean a compound which includes atriplet emitter. Triplet emitters in the present application are takento mean all compounds which are capable of emitting light in the visibleor NIR region through transfer from a triplet state into anenergetically lower state. This is also referred to as phosphorescence.Suitable for this purpose are firstly compounds which contain heavyatoms having an atomic number of greater than 36. Preference is given tocompounds which contain d- or f-transition metals which satisfy theabove-mentioned condition. Particular preference is given here tocorresponding structural units which contain elements of group 8 to 10of the Periodic Table (Ru, Os, Rh, Ir, Pd, Pt). Suitable structuralunits for the polymers according to the invention here are, for example,various complexes, as described, for example, in WO 02/068435 A1, in WO02/081488 A1 and in EP 1239526 A2. Corresponding monomers are describedin WO 02/068435 A1 and in WO 2005/042548 A1. It is preferred inaccordance with the invention to employ triplet emitters which emit inthe visible spectral region (red, green or blue). The triplet emittermay be part of the backbone of the polymer (i.e. in the main chain ofthe polymer) or it may be located in a side chain of the polymer.

Structural units from group 5 are those which improve transfer from thesinglet state to the triplet state and which, employed in support of theabove-mentioned triplet emitter units, improve the phosphorescenceproperties of these structural elements. Suitable for this purpose are,in particular, carbazole and bridged carbazole dimer units, asdescribed, for example, in WO 2004/070772 A2 and in WO 2004/113468 A1.Also suitable for this purpose are ketones, phosphine oxides,sulfoxides, sulfones, silane derivatives and similar compounds, asdescribed, for example, in WO 2005/040302 A1.

Structural units from group 6, besides those mentioned above, are thosewhich have at least one further aromatic structure or another conjugatedstructure which do not fall under the above-mentioned groups, i.e. whichhave only little influence on the charge-carrier mobilities, are notorganometallic complexes or do not influence singlet-triplet transfer.Structural elements of this type can influence the emission colour ofthe resultant polymers. Depending on the unit, they can therefore alsobe employed as emitters. Preference is given here to aromatic structureshaving 6 to 40 C atoms or also tolan, stilbene or bisstyrylarylenederivatives, each of which may be substituted by one or more radicalsR¹. Particular preference is given here to the incorporation of 1,4phenylene, 1,4-naphthylene, 1,4- or 9,10-anthrylene, 1,6-, 2,7- or4,9-pyrenylene, 4,4′-biphenylylene, 4,4″-terphenylylene,4,4′-bi-1,1′-naphthylylene, 4,4′-tolanylene, 4,4′-stilbenylene,4,4″bisstyrylarylene, benzothiadiazole and corresponding oxygenderivatives, quinoxaline, phenothiazine, phenoxazine, dihydrophenazine,bis(thiophenyl)arylene, oligo(thiophenylene), phenazine, rubrene,pentacene or perylene derivatives, which are preferably substituted, orpreferably conjugated push-pull systems (systems which are substitutedby donor and acceptor substituents) or systems such as squarines orquinacridones, which are preferably substituted.

Structural units from group 7 are units which have aromatic structureshaving 6 to 40 C atoms, which are typically used as polymer backbone.These are preferably 4,5-dihydropyrene derivatives,4,5,9,10-tetrahydropyrene derivatives, fluorene derivatives, 9,9′spirobifluorene derivatives, phenanthrene derivatives,9,10-dihydrophenanthrene derivatives, 5,7-dihydrodibenzoxepinederivatives and cis- and trans-indenofluorene derivatives, but inprinciple also all similar structures which, after polymerisation, wouldresult in a conjugated, bridged or unbridged polyphenylene orpolyphenylene-vinylene homopolymer. Here too, the said aromaticstructure may contain heteroatoms, such as 0, S or N, in the backbone ora side chain.

Structural units from group 8 are those which influence the filmmorphology and/or the rheology of the polymers, such as, for example,siloxanes, long alkyl chains or fluorinated groups, but alsoparticularly rigid or flexible units, such as, for example, liquidcrystal-forming units or crosslinkable groups.

Preferred polymers according to the invention are those in which atleast one structural unit has charge-transport properties, i.e. polymerswhich contain, inter alia, at least one unit selected from groups 1 and2.

Preferred compounds according to the invention are polymers whichsimultaneously, besides structural units of the formula (I),additionally contain one or more units selected from groups 1 to 8. Itmay furthermore be preferred for more than one structural unit from onegroup to be present simultaneously.

It is likewise preferred for the polymers according to the invention tocontain units which improve the charge transport and/or chargeinjection, i.e. units from group 1 and/or 2; a proportion of 0.5 to 50mol % of these units is particularly preferred; a proportion of 1 to 30mol % of these units is very particularly preferred.

It is furthermore particularly preferred for the polymers according tothe invention to contain structural units from group 7 and units fromgroup 1 and/or 2. It is particularly preferred for the sum of structuralunits of the formula (I), of units of group 7 and units from group 1and/or 2 of the polymer to be at least 50 mol %, based on all units inthe polymer, where 0.5 to 50 mol % of units are preferably from group 1and/or 2.

The way in which the above-mentioned copolymers can be obtained andwhich further structural elements are particularly preferred for thispurpose is described in detail, for example, in WO 2005/014688 A2. Thisbecomes part of the disclosure content of the present application by wayof reference. It should likewise be emphasised at this point that thepolymer may also have dendritic structures.

The synthesis of the above-described units from groups 1 to 8 and of thefurther emitting units is known to the person skilled in the art and isdescribed in the literature, for example in WO 2005/014689 A2, in WO2005/030827 A1 and in WO 2005/030828 A1. These documents and theliterature cited therein are part of the technical teaching disclosed inthe present application by way of reference.

For the synthesis of the compounds according to the invention, apolymerisation reaction with one or more different monomer buildingblocks is generally carried out, where at least one monomer incorporatedinto the polymer results in structural units of the formula (I).Suitable polymerisation reactions are known to the person skilled in theart and are described in the literature. Particularly suitable andpreferred polymerisation reactions which result in C—C or C—N links arethe following: SUZUKI, YAMAMOTO, STILLE, HECK, NEGISHI, SONOGASHIRA,HIYAMA, ULLMANN, WITTIG or HARTWIG-BUCHWALD polymerisation. The way inwhich the polymerisation can be carried out by these methods and the wayin which the polymers can then be separated off from the reaction mediumand purified is known to the person skilled in the art and is describedin detail in the literature, for example in WO 03/048225 A2, in WO2004/037887 A2 and in WO 2004/037887 A2.

The present application thus also relates to a process for thepreparation of the polymers according to the invention, which ischaracterised in that they are prepared by SUZUKI, YAMAMOTO, STILLE,HECK, NEGISHI, SONOGASHIRA, HIYAMA, ULLMANN, WITTIG or HARTWIG-BUCHWALDpolymerisation.

The dendrimers according to the invention can be prepared by processesknown to the person skilled in the art or analogously thereto. Suitableprocesses are described in the literature, for example in Frechet, JeanM. J.; Hawker, Craig J., “Hyperbranched polyphenylene and hyperbranchedpolyesters: new soluble, three-dimensional, reactive polymers”, Reactive& Functional Polymers (1995), 26(1-3), 127-36; Janssen, H. M.; Meijer,E. W., “The synthesis and characterization of dendritic molecules”,Materials Science and Technology (1999), 20 (Synthesis of Polymers),403-458; Tomalia, Donald A., “Dendrimer molecules”, Scientific American(1995), 272(5), 62-6, WO 02/067343 A1 and WO 2005/026144 A1.

For the synthesis of the polymers according to the invention, thecorresponding monomers of the formula (11) are required.

Monomers which result in structural units of the formula (I) in thepolymers according to the invention are compounds which arecorrespondingly substituted and have at two positions suitablefunctionalities which allow this monomer unit to be incorporated intothe polymer. The present application thus likewise relates to thesemonomers of the formula (II). The symbols and indices R¹, R², m and nused in formula (II) are defined as described in relation to formula(I). The group X represents, identically or differently, a leaving groupwhich is suitable for a polymerisation reaction, so that theincorporation of the monomer building blocks into polymeric compounds isfacilitated. X preferably represents a chemical functionality which isselected, identically or differently, from the class of the halogens,O-tosylates, O-triflates, O-sulfonates, boric acid esters, partiallyfluorinated silyl groups, diazonium groups and organotin compounds.

The basic structure of the monomer compounds can be functionalised bystandard methods, for example by Friedel-Crafts alkylation or acylation.Furthermore, the basic structure can be halogenated by standard methodsof organic chemistry. The halogenated compounds can optionally bereacted further in additional functionalisation steps. For example, thehalogenated compounds can be employed, either directly or afterconversion into a boronic acid derivative or organotin derivative, asstarting materials for the reaction to give polymers, oligomers ordendrimers.

The said methods merely represent a selection from the reactions knownto the person skilled in the art which the latter will be able toemploy, without being inventive, for the synthesis of the compoundsaccording to the invention.

It may be preferred to use the polymers according to the invention notas pure substance, but instead as a mixture (blend) together withfurther polymeric, oligomeric, dendritic or low-molecular-weightsubstances of any desired type. These may, for example, improve theelectronic properties or emit themselves. Mixture above and below istaken to mean a composition which comprises at least one polymericcomponent.

The present application thus furthermore relates to a mixture (blend)which comprises one or more polymers according to the invention, and oneor more further polymeric, oligomeric, dendritic or low-molecular-weightsubstances.

In a further embodiment of the present invention, it is preferred for amixture to comprise a polymer according to the invention containingstructural units of the formula (I) and a low-molecular-weightsubstance.

In a further embodiment according to the invention, it is preferred fora mixture to comprise a polymer according to the invention, an emitter,which is either present in the polymer according to the invention or, asin the above-mentioned embodiments, admixed as low-molecular-weightsubstance, and further low-molecular-weight substances. Theselow-molecular-weight substances can have the same functionalities asmentioned for possible monomer building blocks in groups 1 to 8.

The present application furthermore relates to formulations comprisingone or more polymers according to the invention and at least onesolvent. The way in which solutions of this type can be prepared isknown to the person skilled in the art and is described, for example, inWO 02/072714 A1, in WO 03/019694 A2 and in the literature cited therein.

Suitable and preferred solvents are, for example, toluene, anisoles,xylenes, methyl benzoate, dimethylanisoles, mesitylenes, tetralin,veratrols and tetrahydrofuran or mixtures of the said substances.

These solutions can be used to produce thin polymer layers, for exampleby surface-coating methods (for example spin coating) or by printingprocesses (for example ink-jet printing).

The polymers, mixtures and formulations according to the invention canbe used in electronic or opto-electronic devices or for the productionthereof.

The present application relates to the use of the polymers, mixtures andformulations according to the invention in electronic or opto-electronicdevices, preferably in organic electroluminescent devices (OLED),organic light-emitting electrochemical cells (OLEC), organicfield-effect transistors (OFETs), organic integrated circuits (O-ICs),organic thin-film transistors (TFTs), organic solar cells (O-SCs),organic laser diodes (O-lasers), organic photovoltaic elements ordevices (OPV) or organic photoreceptors (OPCs), particularly preferablyin organic electroluminescent devices (OLED).

The present application is focused on the use of the compounds accordingto the invention in organic electroluminescent devices (OLEDs). However,it is possible for the person skilled in the art, without furtherinventive step, also to employ the compounds according to the inventionfor further uses in other electronic devices.

For the purposes of the present application, it is preferred for thepolymer, oligomer or dendrimer according to the invention to be in theform of a layer (or to be present in a layer) in the electronic device.

The present application thus also relates to a layer, in particular anorganic layer, comprising one or more polymers according to theinvention.

The compounds are preferably used in organic electronic devicescomprising at least one layer comprising one or more of the polymersaccording to the invention. Preference is given to the use, inparticular, in organic electroluminescent devices comprising anode,cathode and at least one emitting layer, characterised in that at leastone layer comprises at least one polymer according to the inventionwhich has structural units of the formula (I).

In a further embodiment, it is preferred for the polymer containingstructural units of the formula (I) to be employed together with anemitting compound in an emitting layer. The mixture of the polymercontaining structural units of the formula (I) and the emitting compoundthen comprises between 99 and 1% by weight, preferably between 98 and60% by weight, particularly preferably between 97 and 70% by weight,very particularly preferably between 95 and 75% by weight, of thepolymer, based on the entire mixture of emitter and matrix material.Correspondingly, the mixture comprises between 1 and 99% by weight,preferably between 2 and 40% by weight, particularly preferably between3 and 30% by weight, very particularly preferably between 5 and 25% byweight, of the emitter, based on the entire mixture of emitter andmatrix material.

In still a further embodiment of the present invention, the polymersaccording to the invention are employed as hole-transport material or ashole-injection material. The polymer is preferably employed in ahole-transport layer or in a hole-injection layer. These hole-injectionlayers according to the invention are, for example, triarylamines,carbazoles, silanes or phosphines.

A hole-injection layer in the sense of the present application is alayer which is directly adjacent to the anode. A hole-transport layer inthe sense of the present application is a layer which is located betweena hole-injection layer and an emission layer. If polymers according tothe invention are used as hole-transport material or as hole-injectionmaterial, it may be preferred for them to be doped withelectron-acceptor compounds, for example withF₄-tetracyanoquinodimethane (TCNQ) or with compounds as described in EP1476881 or in EP 1596445.

In addition, the polymers according to the invention can be used incharge-blocking layers. These charge-blocking layers can consist ofvarious suitable materials, including aluminium oxide, polyvinylbutyral,silane and mixtures thereof. This layer, which is generally applied byknown coating techniques, can be of any effective thickness, preferablyin the range from 0.05 to 0.5 μm.

The present application furthermore relates to electronic oropto-electronic components, preferably organic electroluminescentdevices (OLED), organic light-emitting electrochemical cells (OLEC),organic field-effect transistors (OFETs), organic integrated circuits(O-ICs), organic thin-film transistors (TFTs), organic solar cells(O-SCs), organic laser diodes (O-lasers), organic photovoltaic elementsor devices (OPV) or organic photoreceptors (OPCs), particularlypreferably organic electroluminescent devices having one or more activelayers, where at least one of these active layers comprises one or morepolymers according to the invention. The active layer can be, forexample, a light-emitting layer, a charge-transport layer and/or acharge-injection layer.

The way in which OLEDs can be produced is known to the person skilled inthe art and is described, for example, as a general process in detail inWO 2004/070772 A2, which should be adapted correspondingly for theindividual case.

Preference is given to an organic electroluminescent device,characterised in that one or more layers are produced from solution,such as, for example, by spin coating, or by means of any desiredprinting process, such as, for example, roll to roll, screen printing,flexographic printing or offset printing, but particularly preferablyLITI (light induced thermal imaging, thermal transfer printing), ink-jetprinting, dipping processes or spraying processes. Soluble compounds arenecessary for this purpose. High solubility can be achieved here throughthe substitutions according to the invention.

Apart from cathode, anode and the emitting layer, the organicelectroluminescent device may also comprise further layers. These can beselected, for example, from charge-carrier injection, charge-carriertransport or charge-carrier blocking layer (T. Matsumoto et al.,Multiphoton Organic EL Device Having Charge Generation Layer, IDMC 2003,Taiwan; Session 21 OLED (5)).

However, it should be pointed out that each of these layers does notnecessarily have to be present and in addition a plurality of layershaving the same function may be present.

In a further preferred embodiment of the present invention, the organicelectroluminescent device comprises a plurality of emitting layers,where at least one layer comprises at least one polymer according to theinvention. The emission layers preferably have a plurality of emissionmaxima between 380 nm and 750 nm, resulting overall in this case inwhite emission. Particular preference is given to three-layer systems,where at least one of these layers comprises at least one polymeraccording to the invention and where the three layers exhibit blue,green and orange or red emission (for the basic structure see, forexample, WO 05/011013).

The present application thus relates both to the devices themselves andalso to the use of the polymers according to the invention in thecorresponding devices.

All preferred and not explicitly preferred features of theabove-mentioned polymers according to the invention, the use thereof inelectronic devices and the electronic devices themselves can be combinedwith one another as desired. All resultant combinations are likewisepart of the present application.

The compounds according to the invention preferably have one or more ofthe following advantageous properties on use in organicelectroluminescent devices:

-   1. The polymers according to the invention have a large band gap, so    that deeper-blue singlet emission is achieved for display    applications having a large colour space. The larger band gaps in    the polymers according to the invention additionally enable the use    thereof as host materials, not only for red, but also for green    triplet emission.-   2. The compounds according to the invention increase the lifetime    and efficiency, in particular of blue-emitting organic    electroluminescent devices for high-value applications.

The following examples are intended to explain the present invention ingreater detail without restricting it. In particular, the features,properties and advantages described therein of the defined compounds onwhich the relevant example is based can also be applied to othercompounds which are not mentioned in detail, but fall within the scopeof protection of the claims, unless mentioned otherwise elsewhere.

WORKING EXAMPLES

Preparation of the Monomers

The monomeric compounds for the synthesis of the polymers according tothe invention can be prepared by methods described in the prior art,where the person skilled in the art will be able to apply the methods tothe case specifically present without being inventive.

Thus, the dibenzocycloheptane monomer employed in the polymer accordingto the invention is obtained by the following route:

(D. Vonlanthen et al Eur. J. Org. Chem. 2010, 120)Preparation of the Polymers

Comparative polymer V1 and polymers P1 according to the invention aresynthesised using the following monomers (per cent data=mol %) by SUZUKIcoupling in accordance with the general procedure from WO 03/048225 A2.

Comparative Example 1 Comparative Polymer V1

Example 2 Polymer P1

Examples 3 and 4 Production of PLEDs

The production of a polymeric organic light-emitting diode (PLED) hasalready been described many times in the literature (for example in WO2004/037887 A2). In order to explain the present invention by way ofexample, PLEDs are produced using comparative polymer V1 and polymer P1according to the invention by spin coating.

To this end, use is made of especially prepared substrates fromTechnoprint in a layout designed specifically for this purpose. The ITOstructure (indium tin oxide, a transparent, conductive anode) is appliedto soda-lime glass by sputtering in a pattern such that four 2×2 mmpixels arise with the cathode vapour-deposited at the end of theproduction process.

The substrates are cleaned with DI water and a detergent (Deconex 15 PF)in a clean room and then activated by UV/ozone plasma treatment. An 80nm layer of PEDOT (PEDOT is a polythiophene derivative (Baytron P VAI4083sp.) from H. C. Starck, Goslar, which is supplied as aqueousdispersion) is then applied by spin coating, likewise in the clean room.The spin rate required depends on the degree of dilution and thespecific spin-coater geometry (typically for 80 nm: 4500 rpm). In orderto remove residual water from the layer, the substrates are dried byheating on a hotplate at 180° C. for 10 minutes. Then, under inert-gasatmosphere (nitrogen or argon), firstly 20 nm of an interlayer(typically a hole-dominated polymer, here HIL-012 from Merck) and then65 nm of the polymer layers are applied from toluene solutions(concentration of interlayer 5 g/l, for polymers V1 and P1 between 8 and10 g/I). Both layers are dried by heating at 180° C. for at least 10minutes. The Ba/Al cathode is then applied by vapour deposition in thepattern indicated through a vapour-deposition mask (high-purity metalsfrom Aldrich, particularly barium 99.99% (Order No. 474711);vapour-deposition units from Lesker or others, typical vacuum level5×10⁻⁶ mbar). In order to protect, in particular, the cathode againstair and atmospheric moisture, the device is finally encapsulated andthen characterised.

To this end, the devices are clamped into holders manufacturedspecifically for the substrate size and provided with spring contacts. Aphotodiode with eye response filter can be placed directly on themeasurement holder in order to exclude influences from extraneous light.

The voltages are typically increased from 0 to max. 20 V in 0.2 V stepsand reduced again. For each measurement point, the current through thedevice and the photocurrent obtained is measured by the photodiode. Inthis way, the IVL data of the test devices are obtained. Importantparameters are the measured efficiency at 1000 cd/m² (in cd/A) and thevoltage required for 1000 cd/m².

In order, in addition, to know the colour and the preciseelectroluminescence spectrum of the test devices, the voltage requiredfor 1000 cd/m² is applied again after the first measurement, and thephotodiode is replaced by a spectrum measuring head. This is connectedto a spectrometer (Ocean Optics) by an optical fibre. The colourcoordinates (CIE: Commission International de I'éclairage, standardobserver from 1931) can be derived from the measured spectrum.

The results obtained on use of comparative polymer V1 and polymer P1according to the invention in PLEDs are summarised in Table 1 below.

TABLE 1 Eff. at 1000 U @ cd/m² 1000 cd/m² CIE λ max. Ex. Polymer [cd/A][V] [x/y] [nm] Lifetime [h] 3 V1 5.53 7.9 0.14/0.21 464  400@1000 4 P15.84 8.1 0.14/0.17 455 1100@1000

As can be seen from the results in Table 1, the polymer according to theinvention has both higher efficiency and also a significantly longerlifetime than a comparable polymer of the prior art.

In addition, the polymer according to the invention results indeeper-blue emission.

The invention claimed is:
 1. A polymer comprising one or more structuralunits of the formula (I),

where R¹, R² are on each occurrence, identically or differently, H, D,F, OH, N(R³)₂, a straight-chain, branched or cyclic alkyl, alkoxy orthioalkoxy group having 1 to 40 C atoms, in which, in addition, one ormore H atoms may be replaced by F and in which, in addition, one or morenon-adjacent CH₂ groups may be replaced by O, S, Si(R³)₂, Ge(R³)₂, BR³,NR³, PR³, CO, C═S, C═Se, C═NR³, PO(R³), PS(R³), R³C═CR³, C≡C, SO, SO₂,COO, O(CO)O or CONR³, or a mono- or polycyclic, aromatic orheteroaromatic ring system; R³ are on each occurrence, identically ordifferently, H, F, a straight-chain, branched or cyclic alkyl, alkoxy orthioalkoxy group having 1 to 40 C atoms, in which, in addition, one ormore H atoms may be replaced by F and in which, in addition, one or morenon-adjacent CH₂ groups may be replaced by O, CO, COO or O(CO)O, or amono- or polycyclic, aromatic or heteroaromatic ring system; m, n are,independently of one another, identically or differently, 0, 1, 2 or 3;and the dashed lines represent the bonds to the adjacent structuralunits in the polymer, wherein the proportion of the structural units ofthe formula (I) in the polymer is 1 to 95 mol %, and wherein the polymercontains at least one further structural unit which is different fromthe structural unit of the formula (I).
 2. The polymer according toclaim 1, wherein the structural unit of the formula (I) is selected fromthe structural units of the formulae (Ia) to (Ic)

where the dashed lines in the formulae (Ia), (Ib) and (Ic) represent thebonds to the adjacent structural units in the polymer, and R¹, R², m andn in the formulae (Ia) to (Ic) can adopt the meanings indicated for R¹,R², m and n in relation to formula (I) in claim
 1. 3. The polymeraccording to claim 2, wherein the structural unit of the formula (Ia) isselected from the formulae (Ia1) and (Ia2)

where the dashed lines in the formulae (Ia1) and (Ia2) represent thebonds to the adjacent structural units in the polymer, and the radicalsR¹ in the formulae (Ia1) and (Ia2) can adopt the meanings indicated forR¹ in relation to formula (I) in claim
 1. 4. The polymer according toclaim 1, wherein the polymer has a molecular weight M_(w) in the rangefrom 1,000 to 2,000,000 g/mol.
 5. A mixture comprising at least onepolymer according to claim 1 and additionally one or more compoundsselected from the classes of the polymeric, oligomeric, dendritic andlow-molecular-weight substances.
 6. A formulations comprising at leastone polymer according to claim 1 and at least one solvent.
 7. A methodcomprising utilising the polymer according to claim 1 in organicelectronic devices.
 8. A method comprising utilising the mixtureaccording to claim 5 in organic electronic devices.
 9. An organicelectronic device having one or more active layers, wherein at least oneof these active layers comprises one or more polymers according toclaim
 1. 10. An organic electronic device having one or more activelayers, wherein at least one of these active layers comprises one ormore mixtures according to claim
 5. 11. Organic electronic deviceaccording to claim 8, wherein the device is an organicelectroluminescent device (OLED), an organic light-emittingelectrochemical cell (OLEC), an organic integrated circuit (O-IC), anorganic field-effect transistor (OFET), organic thin-film transistor(OTFT), an organic solar cell (O-SC), an organic laser diode (O-laser),an organic photovoltaic element or a corresponding device (OPV) or anorganic photoreceptor (OPC), preferably an organic electroluminescentdevice (OLED).